I occasionally write some software, but mostly due to not having enough time, it is usually left in a half finished state. You can find most of if on GitHub. Here is a short list with some comments

ReviewIt

A pastebin-like django app allowing inline comments. A live version can be found on AppEngine.

Qidle

A Qt "clone" of the IDLE Python shell. It has some nice features (inline scipy plots, nice autocompletion, history saving), but at the moment it also has a lot of bugs. I had grand plans for it, but too little time. If you want a nice modern shell, use IPython

PicasaFUSE

A FUSE filesystem for Google's PicasaWeb service. Mostly functional, but occasionally crashes.

Comment

A PDF annotation tool. Written when Okular did not have pdf annotation support and the maintainer wasn't very friendly. Nowadays Okular has great support (although, e.g., the version of the poppler library in Ubuntu 12.04 Precise is too old, this ppa helps) and even the free versions of Adobe Reader (only on widows, though) allow commenting.

SkypeProxy

This is the software that generated most interest. It was a utility which could proxy tcp connections through skype. Although it was only a proof of concept and barely worked for light ssh connections, people were interested in it. Nowadays there are better solutions (e.g. telepathy tubes) and I am not even sure the program works with the latest version of skype. Nevertheless, the link points to the sources and there is also a windows installer

Chess for Skype

Play chess with your skype buddies. I have no idea, whether it works with newer versions of skype. I myself only played one or two games with it. Most of my friends on skype don't play chess. It has a windows installer.